"In spite of all, however, the Senate left no means untried to save the State. It exhorted the people to fresh exertions, strengthened the city with guards, and deliberated on the crisis in
a brave and manly spirit. And subsequent events made this manifest. For though
the Romans were on that occasion indisputably beaten in the field, and had lost
their reputation for military prowess; by the peculiar excellence of their
political constitution, and the prudence of their counsels, they not only
recovered their supremacy over Italy, by eventually conquering the Carthaginians,
but before very long became masters of the whole world."

And in Book
VI, An Analysis of the Roman Government he writes : "…that Hannibal was much less filled with joy from having
vanquished the Romans in the field, than he was struck with terror and
astonishment at the firmness and magnanimity what appeared in their
deliberations." He also discusses in IX, 22-26, the Character of Hannibal. That all doesn't help us much though.

"…To Hannibal the
victory seemed too great and too joyous for him to realise all at once. He told
Maharbal that he commended his zeal, but he needed time to think out his plans.
Maharbal replied: "The gods have not given all their gifts to one man. You
know how to win victory, Hannibal,
you do not how to use it." That day's delay is believed to have saved the
City and the empire."

Mommsen, History of Rome, Book 3: From Cannae To Zama: The Crisis (Ancient/Classical History at About.com) writes in Military and Political Position of Hannibal: "[That
aim] was the aim dictated to him by right policy, because,
mighty conqueror though he was in battle, he saw very clearly that on
each
occasion he vanquished the generals and not the city, and that after
each new
battle the Romans remained just as superior to the Carthaginians as he
was
personally superior to the Roman commanders. That Hannibal even at the
height of his fortune never deceived himself on this point, is
worthier of admiration than his most admired battles."

G.P. Baker in Hannibal writes(upon Maharbal's advice to Hannibal)
"All the world thought so. Titus Livius believed that this one day's
delay saved Rome. . . . The world had two thousand years to reflect
over the problem; and Hannibal formed it in a much shorter time. . .
Moreover, among the Carthaginian corps-commanders Maharbal was a
minority of one." And Hannibal's men were exhausted.More on Baker's Book

Adrian Goldsworthy in The Fall of Carthage: The Punic Wars 265-146BC
echoes Dodge's thoughts and points out that Cannae was 250 miles
from Rome, that Rome was not entirely defenseless, and that a siege
would have taken a long time, and also that Hannibal was almost
certainly physically and mentally exhausted.
(Elsewhere, I've read that he did not have the siege material either.)
Goldsworthy also says that on balance the situation seemed very good
and that there was no reason for Hannibal to assume that continued
pressure on Rome would not result in an eventual defeat.

The lone dissenter in my library is Jakob Seibert, Hannibal (in German).
He calls the occasion – or missed occasion – a "verschenkter Sieg" (a
give-away victory) and a "gravierendes Versäumnis" (a serious lapse), and that
Maharbal couldn't have been any more right when he exhorted Hannibal to march on Rome immediately.

B. D. Hoyos, the author of Unplanned Wars: The Origins
of the First and Second Punic Wars (too costly for most of us) wrote an article for Greece &
Rome (2nd Ser., Vol. 30, No. 2,Oct., 1983, pp. 171-180), Hannibal:
What Kind of Genius? (JSTOR, limited access). In it, he seems to be somewhat in the Seibert camp. He too
thinks that Maharbal was right, but also that his
"crowning" victory made Hannibal cautious, and that he preferred a slower strategy. He writes: "This was
virtually a Punic version of cunctatio. It was just about the worst time for
caution to overpower
boldness." He comes to the conclusion that Hannibal
was "a great man who was not quite great enough".

"In spite of all, however, the Senate left no means untried to save the State. It exhorted the people to fresh exertions, strengthened the city with guards, and deliberated on the crisis in
a brave and manly spirit. And subsequent events made this manifest. For though
the Romans were on that occasion indisputably beaten in the field, and had lost
their reputation for military prowess; by the peculiar excellence of their
political constitution, and the prudence of their counsels, they not only
recovered their supremacy over Italy, by eventually conquering the Carthaginians,
but before very long became masters of the whole world."

And in Book
VI, An Analysis of the Roman Government he writes : "…that Hannibal was much less filled with joy from having
vanquished the Romans in the field, than he was struck with terror and
astonishment at the firmness and magnanimity what appeared in their
deliberations." He also discusses in IX, 22-26, the Character of Hannibal. That all doesn't help us much though.